JP2018120999A - Wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate main body made of ceramic and having physical strength, the distance between adjacent element mounting pads on the same surface of the substrate main body can be reduced, and heat from the mounted element can be easily dissipated. Providing a flexible wiring board. SOLUTION: A substrate main body 2a made of ceramics c1 and c2 and having a front surface 3 and a back surface 4 facing each other and a side surface 5 between the peripheral surfaces thereof, and a tip portion 7a on the surface 3 side of the substrate main body 2a from the surface 3 A pair of element mounting pads 6a and 6b formed so as to project outward and a pair of external connection terminals 10a and 10b formed on the surface 3 are provided, and the base portion 7b of the element mounting pads 6a and 6b is formed. It is located in each of a plurality of recesses 3a and 3b formed on the surface 3 of the substrate body 2a, and is electrically connected between the pads 6a and 6b and the part connection terminals 10a and 10b via the first connection wiring 21. A wiring board 1b that is connected and one end of an inner layer wiring 23 formed inside the board main body 2a is individually connected to each of the pads 6a and 6b. [Selection diagram] Fig. 6

Description

  The present invention relates to a wiring board for mounting a light emitting element having a relatively large amount of heat generation on the surface of a board body.

  For example, a plurality of concave portions are individually formed on both surfaces of the ceramic green sheet by grinding by milling, and the obtained ceramic green body is fired to obtain a ceramic sintered substrate in advance. After the precious metal paste or base metal paste is individually applied or filled in each of the recesses of the ceramic sintered substrate, the precious metal paste or the like is fired together with the ceramic sintered substrate, or a metal layer prepared in advance for each of the recesses Or by performing metal spraying in each of the recesses, a wiring circuit is formed on one side of the ceramic substrate, and the lower portion of the conductor layer protruding from the upper portion is embedded, and the ceramic substrate There has been proposed a manufacturing method for obtaining a ceramic wiring circuit board having a heat radiation effect on the other surface and having a lower part of a metal layer protruding from the upper part (see, for example, Patent Document 1).

  However, any of the manufacturing methods disclosed in the method for manufacturing a ceramic wiring circuit board requires a relatively large number of man-hours and increases costs. In addition, when the green sheet is ground by milling to form a plurality of recesses, the distance between adjacent metal layers on the same surface is maintained at a certain level or more in order to maintain the strength of the ceramic sintered substrate. There is a need to. As a result, it may be difficult to arrange a plurality of conductor layers at a high density or downsize the entire printed circuit board.

Japanese Examined Patent Publication No. 6-82921 (pages 1 to 12, FIGS. 1 to 5)

  The present invention solves the problems described in the background art, and includes a substrate body made of ceramic and having physical strength, and the distance between adjacent element mounting pads on the same surface of the substrate body is as much as possible. It is an object of the present invention to provide a wiring board that can be made small and can easily dissipate heat from elements to be mounted to the outside.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the present invention inserts a base portion of a pair of element mounting pads formed on the surface side of the substrate body into a recess formed on the surface of the substrate body, and a tip portion of the pad. The idea is to project both upward and obliquely upward from the surface.
That is, the wiring board of the present invention (Claim 1) is made of ceramic, and has a substrate body having opposed front and back surfaces and side surfaces located in the periphery thereof, and a front portion on the front side of the substrate body from the surface. And a pair of external mounting terminals formed on at least one of the front surface, the back surface, and the side surface of the substrate body, and a wiring board comprising: The base portion of the element mounting pad or a part of the base portion is located in each of a plurality of recesses formed on the surface of the substrate body, and between the element mounting pad and the external connection terminal. Is electrically connected via the first connection wiring, and the inner layer wiring formed inside the substrate body is individually connected to each of the element mounting pads. And

According to the wiring board, the following effects (1) to (5) can be obtained.
(1) The tip portions of the pair of element mounting pads are formed on the surface side of the substrate body so that the tip portions protrude outward (upward and obliquely upward) from the surface. Even when a device with a relatively large calorific value, such as a diode, is mounted, the heat can be dissipated easily and quickly to the peripheral side of each device mounting pad and to the inside of the ceramic constituting the substrate body. Is possible.
(2) Since the bases of the respective element mounting pads adjacent to each other are located and the distance between the concave parts adjacent to each other can be made larger than the distance between the front parts of each of the element mounting pads, it is made of ceramic. The physical strength on the surface side of the substrate body can be kept high.
(3) Since the distance between the tip portions of the element mounting pads adjacent to each other can be minimized so as not to cause a short circuit, a plurality of the element mounting pads are formed at a high density on the surface of the substrate body. In addition, the entire wiring board can be easily downsized.
(4) On the surface of the element mounting pads and external connection terminals exposed on the surface side of the substrate body, the Au layer is formed on the surface layer side through the Ni layer on the base side by electrolytic metal plating through the inner layer wiring. Therefore, it is possible to exhibit both relatively high corrosion resistance and high solder wettability necessary for mounting the element.
(5) The wiring board is provided with at least two ceramic green sheets, at least one of the green sheets is punched, and at least one of the green sheets is provided with a metallized layer and the first connection. Since it is obtained by printing a conductive paste to be a wiring, an inner layer wiring, and a pair of external connection terminals and then performing electrolytic metal plating a plurality of times, it is relatively low compared to the technique described in Patent Document 1. It can be manufactured at a low cost.

The ceramic is, for example, a high-temperature fired ceramic such as alumina or aluminum nitride, or a low-temperature fired ceramic such as glass-ceramic.
The substrate body has a flat plate shape having a front surface and a back surface facing each other, and a side wall is erected along the periphery of the surface on which the plurality of element mounting pads are formed, and is surrounded by the side wall. A configuration in which a cavity is provided and the bottom surface of the cavity is the above surface is also included.
Further, the elements mounted on the element mounting pad are, for example, light emitting elements such as light emitting diodes (hereinafter referred to as LED elements) and laser diodes (hereinafter referred to as LD elements), or power semiconductors. This is a relatively large exothermic element. A pair (two) or more of the element mounting pads having different polarities are formed on the surface side of the substrate body.

Further, the “outside” of “the front side of the substrate body protrudes outside the surface” of the element mounting pad is an upward direction and a diagonally upward direction from the surface side of the substrate body. It shows that it protrudes to both sides.
Furthermore, it is recommended that the element mounting pad be made of copper (hereinafter referred to as Cu) or silver (hereinafter referred to as Ag) from the viewpoint of conductivity and heat dissipation.
Further, the pair of external connection terminals includes at least a pair of plus (+) and minus (−) having different polarities, and is formed on the same surface, the same back surface, the same side surface, or different side surfaces of the substrate body. Alternatively, the pair may be divided into a front surface and a back surface, a front surface and a side surface, or a back surface and a side surface.
Furthermore, the external connection terminals may be two or more pairs in parallel with each other.
The first connection wiring is a name that distinguishes it from the second connection wiring described later.
In addition, the inner layer wiring is formed by electrolytic metal plating on the element mounting pads and external connection terminals exposed on the surface side of the substrate body during manufacture, or on the surface of the element mounting pads and external connection terminals. On the other hand, it is a part (remainder) of the wiring circuit for plating utilized when nickel (hereinafter referred to as Ni) and gold (hereinafter referred to as Au) are successively subjected to electrolytic metal plating. By having such a wiring circuit at the time of manufacture, the wiring board can be obtained relatively easily and at low cost.

  Further, in the present invention, on the surface side of the substrate body, the element mounting pad constitutes a pair of pairs each having a different polarity, and a plurality of sets of the pair of pads are described above. One element mounting pad for each set pad is arranged on the surface side of the substrate body in a plan view, and the other element mount pad in the adjacent set pad is connected to the other set pad via the second connection wiring. In the plurality of sets of sets of pads, one or the other element mounting pad that is not electrically connected via the second connection wiring is connected via the first connection wiring. Also included is a wiring board (Claim 2) individually connected to the pair of external connection terminals having different polarities.

According to the wiring board as described above, the following effects (6) and (7) are further obtained.
(6) By arranging a plurality of the assembly pads in a straight line on the surface of one wiring board, for example, lighting and display means in a form in which a plurality of LED elements and LD elements are arranged in a straight line are highly durable. It can be easily provided with reliability and reliability.
(7) By arranging a plurality of the assembly pads in both a linear shape and a parallel shape, a single wiring board can provide illumination and display means having a relatively large area in the same manner as described above. Become.

Furthermore, the present invention also provides a wiring board (Claim 3) in which the inner layer wiring formed inside the substrate body is individually connected to each element mounting pad constituting the assembly pad. included.
According to this, since the inner layer wiring is individually connected for each of the element mounting pads, the effects (4) and (5) can be achieved more reliably.
Further, the present invention includes a wiring board (claim 4) in which the distance between the element mounting pads adjacent to each other on the surface side of the substrate body is 50 μm or more.
According to this, since an inadvertent short circuit between adjacent element mounting pads can be prevented, the effect (3) can be achieved more reliably.

Further, according to the present invention, on the back surface side of the substrate body, one or a plurality of metal pads at least partially overlapping with the element mounting pads in a plan view are formed (Claim 5). Is also included.
According to this, since the heat generated by the elements mounted above the pair of element mounting pads (assembled pads) can be dissipated to the outside from the back side of the substrate body via the metal pads, the effect described above is achieved. (1) can be further improved.
The metal pad is also preferably made of Cu or Ag from the viewpoint of conductivity and heat dissipation.
The metal pad includes a metal plate formed in a predetermined shape in advance and a metal plate formed in the following form by electrolytic metal plating a plurality of times as in the case of the element mounting pad.

In addition, according to the present invention, the metal pad includes a wiring board in which a base portion is located in a recess formed on the back surface of the substrate body, and a tip portion protrudes outward from the back surface. Claim 6) is also included.
According to this, the heat dissipation of the heat generated by the element can be further enhanced through the base portion and the tip portion of the metal pad, and the effect (1) can be more remarkably exhibited.
The thickness of the ceramic constituting the substrate body located between the base of the element mounting pad and the base of the metal pad is relatively thin, about 50 to 100 μm, to ensure the heat dissipation. Because of this is desirable.
In addition to the form in which the number of the metal pads and the element mounting pads are equal to each other and the bases of the two are opposed to each other inside the substrate body, the number of the pads is singular or different from the plurality of set pads. The metal pad may have a configuration in which at least a part of both bases partially overlap each other in plan view.
Furthermore, in order to obtain a wiring board having the metal pads of the above-described form, a substrate body in which three or more ceramic layers are laminated is used.

The top view which shows the wiring board of one form by this invention. FIG. 2 is a vertical sectional view of the wiring board taken along the line XX in FIG. 1. FIG. 3 is a partially enlarged vertical sectional view of a one-dot chain line portion Y in FIG. 2. The partial expanded vertical sectional view similar to FIG. 3 of the wiring board which is the application form of the said wiring board. FIG. 4 is a schematic view showing an element substrate for obtaining the wiring board shown in FIGS. 1 to 3. (A) is a vertical sectional view showing a wiring board of a different form, (B) is a vertical sectional view showing a modified form of the wiring board of (A). The top view which shows the outline of the raw substrate for obtaining the wiring board shown to FIG. 6 (B). (A), (B) is a top view which shows the outline of the wiring board of a different form further. The top view which shows the outline of the base substrate for obtaining the wiring board shown to FIG. 8 (A).

Hereinafter, modes for carrying out the present invention will be described.
1 is a plan view showing an embodiment of a wiring board 1a according to the present invention, FIG. 2 is a vertical sectional view taken along the line XX in FIG. 1, and FIG. 3 is an alternate long and short dash line in FIG. 3 is a partially enlarged vertical sectional view of a portion Y. FIG.
As shown in FIGS. 1 to 3, the wiring board 1 a has an elongated rectangular (rectangular) shape in plan view, and has a plate-like board body 2 a as a whole, and a long side direction on the surface 3 of the board body 2 a. A plurality of sets of pads 6 arranged in a straight line, and a pair of external connection terminals 10a, 10b individually positioned on both ends of the surface 3 in the long side direction.
The substrate body 2a is formed by integrally laminating ceramic layers c1 and c2, and has a front surface 3 and a back surface 4 that face each other, and long and short side surfaces 5a and 5b located between the peripheries. Yes. The ceramic layers c1 and c2 are composed of, for example, an upper ceramic layer c1 having alumina or aluminum nitride as a main component and having through holes to form a plurality of recesses 3a and 3b, and a flat ceramic layer c2.

As shown in FIGS. 1 to 3, a plurality of sets (four sets in this embodiment) of the set pads 6 arranged linearly along the long side direction on the surface 3 of the substrate body 2a are different from each other ( It is composed of a pair of element mounting pads 6a and 6b (plus and minus).
The element mounting pads 6a and 6b are rectangular (rectangular) in plan view, and have a base portion 7b located in the recesses 3a and 3b opened in the surface 3 of the substrate body 2a, and an outer side than the surface 3 ( That is, it is composed of a heat radiating portion (pad body) 7 composed of a tip portion 7a protruding upward and obliquely upward from the surface 3. The concave portions 3a and 3b are rectangular (rectangular) in plan view, and a similar metallized layer 18 is formed on each bottom surface of the concave portions 3a and 3b and exposed to the outside of the tip portion 7a (upper surface and side surfaces). The Ni layer 8 and the Au layer 9 formed by electrolytic metal plating are respectively coated with a required thickness. As shown in FIG. 3, the distance L1 between the element mounting pads 6a and 6b adjacent to each other at the shortest distance is 50 μm or more in plan view. The distance L1 prevents an inadvertent short circuit between the pads 6a and 6b.

As shown in FIGS. 1 and 2, a pair of external connection terminals 10a and 10b having different polarities are provided on both ends of the surface 3 of the substrate body 2a in the long side direction and the element mounting pads 6a and 6b. It is formed similarly. The external connection terminals 10a and 10b and the element mounting pads 6a and 6b in each adjacent set pad 6 are mutually connected via a first connection wiring 21 formed between the ceramic layers c1 and c2. And it can be individually energized.
Further, in the plurality of sets of set pads 6, the element mounting pads 6a and 6b adjacent to each other are individually electrically connected via the second connection wiring 22 formed between the ceramic layers c1 and c2. Has been.
Further, as shown in FIG. 1 and FIG. 3, the element mounting pads 6a and 6b of each set pad 6 have inner layer wiring 23 reaching either one of the pair of side surfaces 5a of the substrate body 2a. They are connected alternately and individually along the longitudinal direction of the surface 3.

The inner layer wiring 23 is formed between the ceramic layers c1 and c2, and when the wiring board 1a is manufactured, the heat dissipating part 7 is formed by electrolytic copper plating or electrolytic silver plating. This is a part (remainder) of the wiring dedicated to the plating current used when the Ni layer 8 and the Au layer 9 are individually and sequentially coated on the surface of the part 7a by electrolytic Ni plating and electrolytic Au plating.
The heat radiating portion (pad body) 7 is made of Cu or Ag having excellent conductivity and heat conductivity, and the external connection terminals 10a and 10b, the metallized layer 18, the first and second connection wirings 21 and 22, The inner layer wiring 23 is mainly made of W or Mo.
In addition, the same Ni layer and Au layer (not shown) as described above are sequentially coated on the surfaces exposed to the outside of the external connection terminals 10a and 10b.

As shown in FIG. 1 to FIG. 3, a relatively large amount of heat generated by, for example, an LED element is provided above each of the element mounting pads 6 a and 6 b constituting each set pad 6 via a brazing material (not shown). The large element 20 will be mounted later.
As shown in FIGS. 1 and 2, the pair of external connection terminals 10 a and 10 b includes a plurality of elements 20 that are individually mounted on the upper side of each set pad 6, the first connection wiring 21, and the first connection wiring 21. The two connection wirings 22 can be electrically connected to each other. In other words, the pair of external connection terminals 10 a and 10 b and the element mounting pads 6 a and 6 b for each of a plurality of sets of assembly pads 6 include the first connection wiring 21 and the second connection wiring 22 and the assembly pads 6. One series circuit can be formed through a plurality of the elements 20 mounted on the upper side of the circuit.

FIG. 4 is a vertical sectional view similar to FIG. 3 showing an application form of the wiring board 1a.
As shown in FIG. 4, the wiring board 1a of such an application has a substrate body 2b in which three ceramic layers c1 to c3 are integrally laminated, and the lower ceramic layer c3 has an opening on the back surface 4. A plurality of recesses 4a and 4b overlapping the recesses 3a and 3b in plan view are formed. The same metallized layers 18 as those described above are also individually formed on the ceiling surfaces (bottom surfaces) of the recesses 4a and 4b, and an inner layer wiring formed between the metallized layers 18 in an appropriate pattern between the ceramic layers c2 and c3. 24 is electrically connected. In each of the recesses 4a and 4b having the metallized layer 18 on the ceiling surface, a base portion 15b of a heat radiating portion (pad body) 15 constituting the metal pad 14 is located, and the recess 4a is formed on the back surface 4 of the substrate body 2b. , 4b, a front portion 15a is formed on the opening side of the back surface 4 so as to protrude outward from the back surface 4 and be symmetrical to the front portion 7a. The same Ni layer 16 and Au layer 17 as described above are sequentially coated on the surface of each tip portion 15a.

In addition, by making the thickness of the ceramic layer c2 relatively thin, about 50 to 100 μm, the base portions 7b of the element mounting pads 6a and 6b and the metal pads 14 facing each other with the ceramic layer c2 interposed therebetween. The heat transfer between the base portion 15b and the base portion 15b is ensured, and the heat radiation from the back surface 4 side can be efficiently performed.
Further, since the ceramics c1 and c2 are not provided with through holes or via conductors in the portions where the recesses 3a, 3b, 4a and 4b are formed in the substrate bodies 2a and 2b, the substrate bodies 2a and 2b are provided. There is no strength of itself.
Further, the base portion 7b and the base portion 15b may partially overlap in plan view.
In addition, the distance L2 between the pads 6a and 6b in FIG. 4 is the same as the distance L1.
According to the wiring substrate 1a as described above, the tip portions 7a of the plurality of pairs of element mounting pads 6a and 6b are formed so as to protrude outward from the surface 3 of the substrate bodies 2a and 2b. The distance between 3b can be made larger than the distances L1, L2 between the element mounting pads 6a, 6b, and the distances L1, L2 between the front portions 7a can be minimized so as not to cause a short circuit. The effects (1) to (4) are obtained by sequentially covering the Ni pads 8 and 16 and the Au layers 9 and 17 on the surfaces of the mounting pads 6a and 6b, the external connection terminals 10a and 10b, and the metal pads 14, respectively. , (6), (7) can be performed.

FIG. 5 is a plan view showing an element substrate 30 for manufacturing the wiring substrate 1a.
As shown in FIG. 5, the base substrate 30 has a rectangular shape in plan view, and has a pair of ear portions 31 on both sides of the wiring substrate 1a in the longitudinal direction. A virtual cutting plane cf is set between the wiring board 1a and the pair of ears 31.
A pair of recesses 34 that are semicircular in plan view are formed on the side surfaces 36 of the long sides of each pair of ears 31, and plating that has an arc shape in plan view along the inner wall surface of each recess 34 is formed. The electrode 35 for use is formed separately. A main inner layer wiring 32 dedicated to plating formed inside each of the ear portions 31 is connected to the plating electrode 35 via a sub inner layer wiring 33. Between the main inner layer wiring 32 and each of the element mounting pads 6a and 6b in the plurality of sets of assembly pads 6 in the wiring substrate 1a, a plurality of the inner layer wirings 23 crossing the planned cutting plane cf are individually formed. Has been.

In order to obtain the base substrate 30 as described above, a two-layer or three-layer green sheet (not shown) containing alumina powder or the like is prepared in advance, and one of the green sheets is left in a flat plate form. Then, the remaining one or two layers of green sheets were punched, and a plurality of through-holes that became the recesses 3a and 3b and the recesses 4a and 4b were punched. A conductive paste containing W powder or the like is printed in a predetermined pattern on one or both sides of the flat green sheet, and the unfired metallized layer 18, the first and second connection wires 21 and 22, and the main and sub Inner layer wirings 32 and 33 were formed.
Next, the green sheet laminate is formed by laminating and pressing one or two green sheets with the through holes formed on one or both sides of a flat green sheet, and the laminate is opposed to the long sheet. After notching the pair of recesses 34 for each side surface of the side, the unsintered electrode 35 for plating was formed along the inner wall surface of each recess 34. The green sheet laminate in this state was simultaneously fired to obtain the substrate body of the base substrate 31 composed of the ceramic layers c1 and c2 or the ceramic layers c1 to c3.

  Next, the substrate main body is immersed in an electrolytic Cu plating bath, and the heat radiating portion has base portions 7b and 15b in the concave portions 3a, 3b, 4a and 4b and a tip portion 7a protruding outside the surface 3. 7 and a heat radiating portion 15 having a tip portion 15a protruding outside the back surface 4 as necessary. Further, the substrate body on which a plurality of the heat radiating portions 7 and 15 are formed is sequentially immersed in an electrolytic Ni plating bath and an electrolytic Au plating bath, so that the surfaces of the front portions 7a and 15a for the heat radiating portions 7 and 15 are obtained. The Ni layers 8 and 16 and Au layers 9 and 17 were sequentially coated. Then, the obtained base substrate 30 was diced along each of the planned cutting planes cf, and the pair of ear portions 31 were excised. As a result, the wiring board 1a was obtained.

As described above, in order to manufacture the wiring board 1a, a plurality of green sheets are sequentially subjected to stamping, conductive paste printing, lamination / firing, and a plurality of times of electrolytic metal plating. Therefore, compared with the conventional technique described in the background art, it was possible to manufacture at a low cost with fewer and simple processes.
Therefore, it was also found that the wiring board 1a has the effect (5).
The base substrate 30 includes a plurality of the wiring substrates 1a separated by the planned cutting plane cf, and forms the inner layer wiring 23 between the adjacent wiring substrates 1a. These wiring substrates 1a Alternatively, the pair of ears 31 may be provided on both sides.
Further, before the electrolytic Cu plating is applied to the substrate body, the substrate body is immersed in the electrolytic Ni plating bath, and the first and second connection wirings 21 and 22 and the inner layer wirings 32 and 33 are energized. After forming an Ni layer on the surface of each metallized layer 18 by performing electrolytic Ni plating, the substrate body including the Ni layer is heated to about 500 to 900 ° C. and subjected to heat treatment for holding for a predetermined time. Also good. By performing the plating step and the heat treatment step, the Ni layer is formed between the base portions 7b and 15b of the heat radiating portions 7 and 15 and the metallized layer 18, so that the adhesion strength between the two is enhanced. The wiring board 1a can be obtained.

FIG. 6A is a vertical sectional view showing a wiring board 1b having a different form from the above.
As shown in FIG. 6A, the wiring board 1b is composed of ceramic layers c1 and c2, and has a plate-like board body having opposed front and rear surfaces 3 and 4, and a side surface 5 located between these surfaces. 2a, a pair of element mounting pads 6a and 6b (a set of assembled pads 6) formed on the center side in plan view on the surface 3 of the substrate body 2a, and a pair formed on the peripheral side of the surface 3 External connection terminals 10a and 10b.
The element mounting pads 6a and 6b have their base portions 7b located in the same recesses 3a and 3b as described above, and the same metallized layer 18 formed for each bottom surface of the recesses 3a and 3b includes a ceramic layer. One end of a pair of first connection wirings 21 formed apart from each other between c1 and c2 is individually connected. The pair of first connection wirings 21 can be individually connected to the external connection terminals 10a and 10b located on the surface 3 via via conductors 19 penetrating the ceramic layer c1 along the thickness direction, and The other end of each first connection wiring 21 reaches each of the opposing side surfaces 5 individually.

Further, for each metallized layer 18, one end of an inner layer wiring 23 formed between the ceramic layers c1 and c2 is connected along a direction orthogonal to the first connection wiring 21 in a plan view. The other end reaches a side surface 5 (not shown) positioned in the front-rear direction in FIG.
Further, as shown in FIG. 6A, the external connection terminals 10a and 10b are sequentially covered on the terminal body 11 formed on the surface 3 of the substrate body 2a and its surface (upper surface and side surface or peripheral surface). The Ni layer 12 and the Au layer 13 are provided.
Similarly to the above, when the element 20 is mounted over the pair of element mounting pads 6a and 6b, the pair of external connection terminals 10a and 10b are connected to the left and right via conductors 19 and the first connection in FIG. One series circuit that can conduct each other can be formed through the wiring 21, the metallized layer 18, the pads 6 a and 6 b, and the element 20.
The terminal body 11 and the via conductor 19 are mainly made of W or Mo.
Further, the wiring board 1b can be manufactured in a multi-piece configuration in which a plurality of the wiring boards 1b are arranged adjacent to each other vertically and horizontally in a plan view in accordance with the base substrate 31.

FIG. 6B is a vertical sectional view similar to the above, showing a wiring board 1c which is a modification of the wiring board 1b.
As shown in FIG. 6B, the wiring board 1c also has the same substrate body 2a, element mounting pads 6a and 6b that become a set of assembled pads 6, a metallized layer 18, a first connection wiring 21, and An inner layer wiring 23 is provided. The wiring board 1c is different from the wiring board 1b in that instead of the external connection terminals 10a and 10b, a pair of external connection terminals 25a and 25b individually formed on a pair of side surfaces 5 opposed by the board body 2a are provided. It is a point.
The external connection terminals 25a and 25b each have a semicircular recess 26 formed vertically between the pair of side surfaces 5 between the front surface 3 and the back surface 4 in plan view, and along the inner wall surface of each recess 26. A pair of terminal bodies 27 having a circular arc shape in plan view are individually formed, and an Ni layer 28 and an Au layer 29 are sequentially coated along the inner wall surface of each terminal body 27. The terminal body 27 is also mainly made of W or Mo.

FIG. 7 is a plan view showing an element substrate 40 for obtaining a large number of wiring substrates 1c by taking an example of a manufacturing method for obtaining the wiring substrate 1c.
The base substrate 40 is composed of the ceramic layers c1 and c2, and as shown in FIG. 7, the three wiring boards 1c are continuously arranged in the left-right direction in the plan view, and between and around them. A virtual cutting planned surface cf is set along the outer peripheral side of the cutting planned surface cf, and an ear 41 having a rectangular frame shape in plan view surrounds the outer peripheral side of the cutting planned surface cf. In FIG. 7, the scheduled cutting surfaces cf between the wiring boards 1 c arranged along the left-right direction and the scheduled cutting surfaces cf on the outer peripheral side of the wiring boards 1 c at both the left and right ends are these scheduled cutting surfaces. A plurality of cylindrical conductors 38 each having a cylindrical shape as a whole and having a circular hollow portion 39 vertically on the center side in plan view are formed individually across the intermediate portion of cf.
Between the plurality of cylindrical conductors 38 and the element mounting pads 6a or the element mounting pads 6b of the set pads 6 that are individually adjacent to the plurality of cylindrical conductors 38, the same first connection wirings 21 as described above are individually formed. ing.

A pair of recesses 34 and plating electrodes 35 similar to those described above are individually formed in the middle of each of the long side surfaces 36 facing each other on the base substrate 40. The plating electrode 35 is connected to the element mounting pads 6a for each set pad 6 through the sub-inner layer wiring 33, the main inner layer wiring 32, and the plurality of inner layer wirings 23 formed between the ceramic layers c1 and c2. It is possible to conduct individually with either one of 6b.
The base substrate 40 also uses the above-described two-layer green sheet, punching for each required position in one green sheet, printing formation of conductive paste on both sides or one side of the one-layer or two-layer green sheet, After the green sheet is laminated and pressure-bonded, the conductive paste is applied to the inner wall surface of the through hole penetrating the obtained green sheet laminate, and the green sheet laminate is fired, the above-described electrolytic metal plating is performed a plurality of times. Can be easily manufactured.

However, when the above-described electrolytic metal plating is performed a plurality of times on the wiring substrate 1c, some processes are different as follows.
In the manufacturing method described above, electrolytic Cu plating was performed on the fired base substrate body. However, when manufacturing the wiring substrate 1c, the inner peripheral surface of the cylindrical conductor 38 is not covered with a Cu layer. Perform masking. Next, after the heat radiation part 7 is formed by electrolytic Cu plating, the masking is removed and immersed in an electrolytic Ni plating bath and an electrolytic Au plating bath sequentially. By such a method, the cylindrical conductor 38 is configured to have no hollow layer 39 and no Cu layer. Thereafter, the wiring substrate 1c can be obtained by performing dicing along the planned cutting plane cf.

According to the wiring boards 1b and 1c as described above, the effects (1) to (5) can be achieved.
The wiring boards 1b and 1c may further include the board body 2b formed by laminating the ceramic layers c1 to c3 and one or more metal pads 14 on the back surface 4 side.
Further, the wiring boards 1a and 1b may be configured such that the first connection wiring 21 is formed along the surface 3 of the board body 2a (2b), as exemplified by the one-dot chain line in FIG. good. In such a configuration, the Ni layer and the Au layer are also sequentially coated on the surface exposed to the outside of the first connection wiring 21.

FIG. 8A is a plan view showing a further different form of the wiring board 1d.
As shown in FIG. 8A, the wiring board 1d includes a board body 2a having a rectangular shape in plan view and a pair of upper and lower external connection terminals 10a formed along the left side of the surface 3 of the board body 2a. , 10b and two sets of pad pads 6 (up to 4 sets in total) arranged in the upper and lower directions in the surface 3 as shown in the figure. The pair of external connection terminals 10a and 10b and the element mounting terminals 6a and 6b for each adjacent set pad 6 are connected by the same first connection wiring 21 formed in the substrate body 2a. ing. Further, as shown in FIG. 8A, on the surface 3 of the substrate body 2a, between the element mounting pads 6a and 6b for each adjacent set pad 6 and for each set pad 6 on the right side in the drawing. The mounting pads 6a and 6b are individually connected by the same second connection wiring 22 formed in the substrate body 2a.

Further, as shown in FIG. 8A, on the surface 3 of the substrate main body 2a, one of the element mounting terminals 6a and 6b in a total of four sets of set pads 6 of two sets arranged side by side, Between the upper and lower side surfaces 5 in the figure of the main body 2a, the same inner layer wirings 23 as those described above are individually formed. In addition, on the surface 3 of the substrate main body 2a, a horizontal inner layer wiring 23 formed in the substrate main body 2a is provided at a portion surrounded by a total of four set pads 6 of two sets arranged side by side. In addition, a plurality of vertical inner layer wirings 23 connecting the inner layer wiring 23 and one of the element mounting terminals 6a and 6b for each set pad 6 are formed.
That is, the wiring substrate 1d is connected to the first connection wiring 21 and the pair of upper and lower portions between the pair of upper and lower external connection terminals 10a and 10b provided on the left side in the figure on the surface 3 of the substrate body 2a in plan view. A total of four sets of set pads 6, second connection wirings 22 formed between adjacent element mounting terminals 6 a and 6 b between adjacent set pads 6, and element mounting terminals 6 a and 6 b in each set pad 6. A horizontal U-shaped series circuit shown in the figure can be formed via the element 20 mounted on the upper side of the element.

FIG. 8B is a plan view showing a wiring board 1e having a different form according to the present invention.
As shown in FIG. 8B, the wiring board 1e includes a pair of left and right external connection terminals provided on the side 5 of the left and right short sides of the surface 3 of the board 2a. 10a and 10b, and two sets of pad pads 6 (up to four sets in total) arranged side by side in the figure on the surface 3 are provided.
Between the pair of left and right external connection terminals 10a and 10b and one of the element mounting pads 6a and 6b for each of the two pairs of upper and lower sets of pads 6 adjacent to each other, the same branching as described above is performed in the middle. The first connection wiring 21 can be made conductive. Further, as shown in FIG. 8B, on the surface 3 of the substrate body 2a, the element mounting pads 6a and 6b for each set pad 6 adjacent in the left-right direction are formed in the substrate body 2a. Further, they are connected by the same second connection wiring 22 as described above.

Further, in the surface 3 of the substrate body 2a, a portion surrounded by a total of four sets of the set pads 6 in two sets arranged vertically is provided in the substrate body 2a as shown in FIG. 8B. And a plurality of vertical inner layer wirings 23 connecting between the inner layer wirings 23 and one of the element mounting terminals 6a and 6b for each set pad 6 are formed. In addition, a wide portion having a circular shape in plan view is formed in the middle of the horizontal inner layer wiring 23, and a via conductor 19 penetrating the ceramic layer c2 on the lower layer side is connected to the center of the wide portion. An inner layer wiring (not shown) reaching any one of the side surfaces 5 is connected to the tip of the via conductor 19.
That is, the wiring board 1e includes the first connection wiring 21 and the pair of upper and lower sides between the pair of left and right external connection terminals 10a and 10b provided on the left and right side surfaces 5 side in the figure on the surface 3 of the board body 2a in plan view. A total of four sets of set pads 6 each, second connection wirings 22 formed individually between adjacent element mounting terminals 6a and 6b between the adjacent set pads 6 on the left and right, and element mounting on each set pad 6 One parallel circuit can be formed in plan view through the element 20 mounted on the terminals 6a and 6b.
The wiring board 1e can be manufactured according to the raw substrate 40.

FIG. 9 is a plan view showing a base substrate 42 for obtaining the wiring substrate 1d.
The substrate 42 is composed of the ceramic layers c1 and c2, and as shown in FIG. 9, the wiring substrate 1d is disposed on the center side in plan view, and the periphery of the wiring substrate 1d is cut by a planned cutting surface cf. The segmented plan view surrounds the rectangular frame-shaped ear portion 43.
In the element substrate 42 in a plan view, a recess 34 and a plating electrode 35 similar to those described above are formed in the middle of a pair of upper and lower side surfaces 44, and the element mounting terminal for each of the adjacent assembly pads 6 with the plating electrode 35. 6b is electrically connected through the sub inner layer wiring 33, the main inner layer wiring 32, and the same inner layer wiring 23 as described above.
Further, in the base substrate 42 in plan view, a recess 34 and a plating electrode 35 similar to those described above are formed in the middle of the left side surface 44, and the plating electrode 35 and two sets of upper and lower sides are provided. Between the element mounting pads 6 a for each pad 6, the illustrated horizontal inner layer wiring 23 formed in the middle of the substrate body 2 a and a plurality of vertical inner layer wirings 23 branched from the inner layer wiring 23 Via, it is possible to conduct.

The base substrate 42 can be easily manufactured in the same manner as the base substrate 40.
Therefore, the effects (1) to (7) can be achieved by the wiring boards 1d and 1e as described above.
The wiring boards 1d and 1e may further include the board body 2b formed by laminating the ceramic layers c1 to c3 and one or more metal pads 14 on the back surface 4 side.

The present invention is not limited to the embodiments described above.
For example, the ceramic constituting the substrate bodies 2a and 2b may be a high-temperature fired ceramic such as mullite, or a low-temperature fired ceramic such as glass-ceramic. In the latter case, Cu or Ag that can be fired simultaneously with the glass-ceramic or the like is applied to the first and second connection wires 21 and 22.
The substrate bodies 2a and 2b have a shape in which a side wall having a rectangular frame shape is projected along the periphery of the surface 3, and the bottom surface of the cavity surrounded by the side wall also serves as the surface 3. It is good also as a form.
Further, the wiring boards 1b and 1c have a plurality of sets of set pads 6 on the surface 3 side of the substrate body 2a (2b), and one or a plurality of sets depending on the elements 20 to be mounted along with these sets. A series circuit or a parallel circuit may be configured.

One of the external connection terminals 10a, 10b, 25a, and 25b is formed on the surface 3 of the substrate body 2a, 2b, and the other is any of the side surfaces 5, 5a, 5b of the substrate body 2a, 2b. Alternatively, either one may be formed on the front surface 3 of the substrate bodies 2a and 2b, and the other may be formed on the back surface 4 of the substrate bodies 2a and 2b.
Further, the base portion 7b of the element mounting pads 6a and 6b and the base portion 15b of the metal pad 14 may be divided into a plurality of parts (for example, exhibiting a clog shape in a vertical cross section). The recesses 3a, 3b, 4a, 4b are also formed in the same number. In this case, by increasing the contact area between the element mounting pads 6a and 6b and the metal pad 14 and the substrate bodies 2a and 2b, good heat dissipation can be obtained and higher bonding strength can be ensured. You can also.
In addition, the wiring boards 1d and 1e may be configured such that a plurality of sets of series circuits or a plurality of sets of parallel circuits can be used together via elements 20 to be mounted later.

  According to the present invention, a substrate main body made of ceramic and having physical strength is provided, and the distance between adjacent element mounting pads on the same surface of the substrate main body can be reduced, and the heat of the mounted element is externally transmitted. A wiring board capable of easily dissipating heat can be provided.

1a to 1e ................... Wiring boards 2a, 2b ..................... PCB main body 3. ........................ Surface 3a , 3b ..................... Recess 4 ......... ……………………………… Back 5, 5, 5a, 5b ………………… Side 6 ……… ……………………………… Assembly pads 6a, 6b …………………………… Element mounting pads 7a, 15a ………………………… Previous parts 7b, 15b ………………………… Base 10a, 10b, 25a, 25b… External connection terminal 14 …………………………………… Metal pad 21 ………………………… ………… First connection wiring 22 …………………………………… Second connection wiring 23 …………………………………… Inner layer connection wiring c1 to c3 …… ……………………… Ceramic layer (insulating material)
L1, L2 …………………………… Distance

Claims (6)

A substrate main body made of ceramic and having opposing front and back surfaces and side surfaces located in the periphery thereof, and at least a pair of elements formed on the front surface side of the substrate main body so that the front portion protrudes outward from the surface A wiring board comprising a pad and a pair of external connection terminals formed on at least one of the front surface, the back surface, and the side surface of the substrate body,
The base part of the element mounting pad, or a part of the base part is located in each of the plurality of recesses formed on the surface of the substrate body,
The element mounting pad and the external connection terminal are electrically connected via a first connection wiring,
For each element mounting pad, the inner layer wiring formed inside the substrate body is individually connected.
A wiring board characterized by that. On the surface side of the substrate body, the element mounting pad constitutes a pair of pads each having a pair of different polarities,
The plurality of sets of the set pads are arranged linearly or in parallel in a plan view on the surface side of the substrate body, and one element mounting pad for each set pad is mounted on the other element in the adjacent set pad And can be conducted through the pad and the second connection wiring,
In the plurality of sets of sets of pads, one or the other element mounting pad that is not electrically connected via the second connection wiring is a pair of the polarities that are different from each other via the first connection wiring. Individually connected to the external connection terminal,
The wiring board according to claim 1. The inner layer wiring formed inside the substrate body is individually connected to each element mounting pad constituting the set pad,
The wiring board according to claim 1 or 2, wherein On the surface side of the substrate body, the distance in plan view between the element mounting pads adjacent to each other is 50 μm or more.
The wiring board according to any one of claims 1 to 3, wherein On the back side of the substrate body, a single or a plurality of metal pads at least partially overlapping with the element mounting pads in plan view are formed.
The wiring board according to any one of claims 1 to 4, wherein the wiring board is provided. The metal pad is formed such that a base portion is located in a recess formed on the back surface of the substrate body, and a tip portion protrudes outward from the back surface.
The wiring board according to claim 5.

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